Azulenesulfonium Salts: Accessible, Stable, and Versatile Reagents for Cross-Coupling

Area of Science:

• Organic Chemistry
• Synthetic Chemistry

Background:

• Azulenes are non-benzenoid aromatic compounds with unique electronic properties.
• Azulenyl halides are known to be unstable and difficult to synthesize purely.
• Cross-coupling reactions are vital for forming carbon-carbon bonds in organic synthesis.

Purpose of the Study:

• To develop stable and readily preparable azulene derivatives for use in cross-coupling reactions.
• To investigate the utility of azulenesulfonium salts as pseudohalides in Suzuki-Miyaura coupling.
• To compare the stability and reactivity of azulenesulfonium salts with azulenyl halides.

Main Methods:

• Electrophilic Aromatic (SE Ar) substitution reaction on azulenes to form azulenesulfonium salts.
• Purification and characterization of the synthesized azulenesulfonium salts.
• Application of azulenesulfonium salts as pseudohalides in Suzuki-Miyaura cross-coupling reactions with various coupling partners.

Main Results:

• Azulenesulfonium salts were successfully synthesized from azulenes via SE Ar reaction.
• These azulenesulfonium salts demonstrated good bench-stability.
• Effective application of azulenesulfonium salts in Suzuki-Miyaura reactions with diverse substrates was confirmed.

Conclusions:

• Azulenesulfonium salts represent a stable and viable alternative to unstable azulenyl halides.
• The developed method provides a convenient route to functionalized azulenes via cross-coupling.
• Azulenesulfonium salts are promising reagents for synthetic organic chemistry, particularly in Suzuki-Miyaura couplings.